First off, before I boguht this, I did a lot of research! I was initially going to fork out big money for a Tempurpedic. I spoke to a guy who actually made mattresses and he told me the important thing about memory foam is that you want one with at least a 5lb density, that even a tempurpedic would have sags. I was about 6 months pregnant sleeping on a pillow top that was only 4 years old that I paid big money for and it had sags. My back was hurting so bad and I had a severe case of sciatica. I read all the reviews and decided on this mattress and bought a 3 inch topper as well for the softness. I bought the medium firmness. My husband is 6ft2in and about 200 lbs. I'm 5ft5in and currently 160 lbs with the pregnancy but normally only about 120 lbs. The first night I slept on it, I woke up with no back pain! It was heaven. My husband loves it too. There was no smell, it aired out in a few hours and I absolutely love it. There hasn't been any sag, I've had it for only 2 months but plan on flipping the topper each month. Oh, important piece of info, memory foam also sags with higher body temperature so if you run hot, buy a memory foam with a cooling feature. Otherwise, for the money, the quality, fast shipping, and comfort is awesome!!